1. Field of the Invention
The present invention relates to a vital information measuring device for non-invasively detecting various vital information from a human body, and more particularly to a vital information measuring device adapted to measure vital information for a long time.
2. Description of the Related Art
There are known a pulse oximeter, a PSG (polysomnography), and a holter monitor, as examples of a vital information measuring device for non-invasively detecting vital information from a human body, particularly, as a vital information measuring device requiring a long time vital information detection. As shown in FIG. 25, a pulse oximeter 100 is used in such a manner that: a probe 101 equipped with a light emitter and a light detector is detachably attached to a finger of a living body i.e. a subject; light is projected onto a living body of the subject i.e. a finger of the subject to be measured to measure a change in the amount of light transmitted through the living body as a pulse signal; and a change in blood oxygen saturation with time during the subject's sleep is obtained by performing moving-averaging with respect to measurement values at each sampling frequency. The pulse oximeter 100 is constructed in such a manner that the probe 101 and a device main body 102 as individual components are electrically connected by a cable 103. Generally, the pulse oximeter 100 is detachably attached to the subject by attaching the device main body 102 around a wrist of the subject by way of a wristband 104, and by securely holding a fingertip of the subject by the probe 101, with the cable 103 extending along the back of the subject's hand.
The PSG is provided with various sensor devices for detecting, in addition to the blood oxygen saturation, various assessment parameters such as pulse waveforms, air flow rates through mouth or nose, snoring sounds, body positions/body movements, chest and abdominal movements in respiration, and electrocardiographic waveforms. The PSG is a measuring device for diagnosing sleep apnea syndrome (SAS) or the like by analysis and display of the measurement results. Similarly to the pulse oximeter, the PSG is composed of a device main body and the various sensor devices which are provided independently of each other. Generally, the device main body of the PSG device is detachably attached to or around the body trunk portion of a subject; and the sensor devices, which are detachably attached to their appropriate sites of the subject, and the device main body are electrically connected by way of cables.
The holter monitor is generally composed of electrodes for detecting an action potential of the subject's heart, and a receiver for receiving data detected from the electrodes. The holter monitor is a measuring device for performing data measurement under a condition that the subject performs a normal activity for one day or so, with five or so electrodes being attached to the chest of the subject, and the receiver being mounted on the waist of the subject. After the measurement completion, the data stored in the receiver is outputted to a predetermined analyzer for an electrocardiographic waveform analysis, so that a time interval (RR-interval) between two consecutive R waves of the electrocardiogram, or the like is obtained. Generally, the electrodes and the receiver are connected by cables. There is also known a cordless measuring device which is constructed to perform radio communication between electrodes and a receiver.
Also, there is known a disposable pulse oximeter, in which solely a sensor device provided with a light emitter and a light receiver is mounted on a flexible substrate for pulse oximetry measurement. There is also known a vital information measuring device, wherein a sensor which is attached to a subject for detecting vital information on the subject has a radio transmitting function, and the measuring device has a controller for controlling an operation of the sensor, and receiving the vital information sent from the sensor.
The pulse oximeter or the PSG has the cable e.g. the cable 103 shown in FIG. 25 for electrically connecting the sensor device to the device main body. These measuring devices are required to be attached to the subject continuously for a long time during his or her sleep. However, if the cable gets hung up in a bedding item or the like, the sensor device may be detached from the attached site of the subject. Also, the subject may feel discomfort or stress because the measuring device is attached to the subject's body, with the cable entangled. Particularly, since the PSG has a large number of sensor devices, the subject may even feel difficulty in rolling over in his or her sleep, which may inhibit good sleep, and resultantly fail to obtain accurate measurement data. The same drawback is involved in the former conventional arrangement i.e. the disposable pulse oximeter, because the flexible substrate for mounting the sensor device thereon, and the oximeter main body are connected by the cable.
The cordless holter monitor and the latter conventional arrangement i.e. the cordless vital information measuring device are free from the drawback that the cable may get hung up. However, the holter monitor and the cordless vital information measuring device have drawbacks that the subject has to carry the receiver for wirelessly receiving a detection signal from the electrodes, and to carry the controller for wirelessly receiving the vital information detected by the sensor, respectively. In both of the cases, despite the cordless arrangement, the subject may feel stress resulting from carrying some parts of the measuring device. Also, these arrangements essentially fail to solve the inconvenience due to the fact that the sensor device and the device main body are provided independently of each other.